Ultra-high-pressure liquid chromatography–tandem mass spectrometry method for the determination of alkylphenols in soil

A novel method has been developed for the determination of alkylphenols in soil by ultra-high-pressure liquid chromatography employing small particle sizes, combined with tandem mass spectrometry. Soil samples were extracted with pressurized liquid extraction (PLE) and then cleaned with solid-phase extraction (SPE). The extracts were separated on C18 column (1.7 μm, 50 mm × 2.1 mm) with a gradient elution and a mobile phase consisting of water and acetonitrile, and then detected by an electrospray ionization tandem mass spectrometry in negative ion mode with multiple reaction monitoring (MRM). Compared with traditional liquid chromatography, it took ultra-high-pressure liquid chromatography much less time to analyze alkylphenols. Additionally, the ultra-high-pressure liquid chromatography/tandem mass spectrometry method produces satisfactory reliability, sensitivity, and accuracy. The average recoveries of the three target analytes were 74.0–103.4%, with the RSD < 15%. The calibration curves for alkylphenols were linear within the range of 0.01–0.4 μg/ml, with the correlation coefficients greater than 0.99. When 10 g soil sample was used for analysis, the limits of quantification (LOQs) of the three alkylphenols were all 1.0 μg/kg.     

Determination of neonicotinoid insecticides residues in eels using subcritical water extraction and ultra-performance liquid chromatography–tandem mass spectrometry

A rapid, sensitive, and environmental-friendly multi-residue method has been developed for the simultaneous determination of seven neonicotinoid insecticides (dinotefuran, nitenpyram, thiamethoxam, imidacloprid, clothianidin, acetamiprid, and thiacloprid) residues in eel samples. Subcritical water extraction was investigated as a novel and alternative technology for the extraction of neonicotinoids from eel matrices and the results were compared with the conventional ultrasonic and shaking extraction. The target compounds were identified and quantitatively determined by ultra-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC–MS/MS) operated in multiple reaction monitoring mode. Under the current optimized chromatographic conditions, each LC run was completed in 5 min. Average recoveries of the seven analytes from fortified samples ranged between 84.6% and 102.0%, with relative standard deviations (RSD) lower than 10.8%. The limits of detection (LODs) and quantification (LOQs) for neonicotinoids were in the ranges of 0.12–0.36 μg kg⁻¹ and 0.42–1.12 μg kg⁻¹, respectively. The proposed method is fast, sensitive, easy to perform, water-based thus more environmentally acceptable, making it applicable for high-throughput monitoring of insecticides residues in aquatic products.     

Simultaneous determination of NOGE-related and BADGE-related compounds in canned food by ultra-performance liquid chromatography–tandem mass spectrometry

An improved analytical method enabling rapid and accurate determination and identification of bisphenol F diglycidyl ether (novolac glycidyl ether 2-ring), novolac glycidyl ether 3-ring, novolac glycidyl ether 4-ring, novolac glycidyl ether 5-ring, novolac glycidyl ether 6-ring, bisphenol A diglycidyl ether, bisphenol A (2,3-dihydroxypropyl) glycidyl ether, bisphenol A (3-chloro-2-hydroxypropyl) glycidyl ether, bisphenol A bis(3-chloro-2-hydroxypropyl) ether, and bisphenol A (3-chloro-2-hydroxypropyl) (2,3-dihydroxypropyl) ether in canned food and their contact packaging materials has been developed by using, for the first time, ultra-performance liquid chromatography coupled with tandem mass spectrometry. After comparison of electrospray ionization and atmospheric pressure chemical ionization in positive and negative-ion modes, tandem mass spectrometry with positive electrospray ionization was chosen to carry out selective multiple reaction monitoring analysis of novolac glycidyl ethers, bisphenol A diglycidyl ether, and its derivatives. The analysis time is only 5.5 min per run. Limits of detection varied from 0.01 to 0.20 ng g(-1) for the different target compounds on the basis of a signal-to-noise ratio (S/N) = 3; limits of quantitation were from 0.03 to 0.66 ng g(-1). The relative standard deviation for repeatability was <8.01%. Analytical recovery ranged from 87.60 to 108.93%. This method was successfully applied to twenty samples of canned food and their contact packaging materials for determination of migration of NOGE, BADGE, and their derivatives from can coatings into food.     

Rapid determination of 1,1-dimethylhydrazine transformation products in soil by accelerated solvent extraction coupled with gas chromatography–tandem mass spectrometry

A method for the analytical extraction of mobile species of eightmain transformation products of 1,1-dimethylhydrazine (formaldehyde dimethylhydrazone, acetaldehyde dimethylhydrazone, 2-furaldehyde dimethylhydrazone, 1,1,4,4-tetramethyl-2-tetrazene, N,N-dimethylformamide, N-nitrosodimethylamine, 1-methyl-1H-1,2,4-triazole, and 1-formyl-2,2-dimethylhydrazine) from soils using subcritical acetonitrile at a pressure of 100 bar is proposed. The effects of temperature, number of extraction cycles, and the moisture content of soil samples on the recovery of analytes were studied. It was found that, for soils with high concentrations of lignin humic substances, efficient extraction can be attained with an addition of significant amounts of alkali to the soil (2.5 g/g). Under the optimum conditions, the recovery of analytes was higher than 70% at the extraction time no more than 30 min. A combination of the proposed sample preparation approach with analysis by gas chromatography–tandem mass spectrometry (GC-MS/MS) ensures the determination of the products of unsymmetrical dimethylhydrazine (UDMH) transformation in complex matrixes, such as soils with high concentrations of organic substance with detection limits from 1.8 to 15 µg kg^–1 using the direct injection of the extract into the chromatography system. The error of determination at a confidential probability of 0.95 was not worse than 15% even for analyte concentrations close to lower limit of quantitation (LLOQ) values. The method developed is a significant improvement compared to the highly efficient methods previously reported in literature differing from them with simple sample preparation, rapidity, low consumption of reagents, the possibility of simultaneous determination of eight compounds and 1–2 orders of higher sensitivity. It was successfully used for the analysis of real samples of peaty soil from the place of impact of the first step of a carrier rocket.     

Development and validation of a pressurized liquid extraction liquid chromatography–tandem mass spectrometry method for perfluorinated compounds determination in fish

This paper describes the development and validation of an analytical methodology to determine eight perfluorinated compounds (PFCs) in edible fish using pressurized liquid extraction (PLE) with water and solid-phase extraction (SPE) with an ion-exchanger as extraction and pre-concentration procedures, followed by liquid chromatography–quadrupole-linear ion trap mass spectrometry (LC–QqLIT–MS). The rapidity and effectiveness of the proposed extraction procedure were compared with those most commonly used to isolate PFCs from fish (ion-pairing and alkaline digestion). The average recoveries of the different fish samples, spiked with the eight PFCs at three levels (the LOQ, 10 and 100 μg kg⁻¹ of each PFC), were always higher than 85% with relative standard deviation (RSD) lower than 17%. A good linearity was established for the eight PFCs in the range from 0.003–0.05 to 100 μg kg⁻¹, with r > 0.9994. The limits of quantification (LOQs) were between 0.003 and 0.05 μg kg⁻¹, which are well below those previously reported for this type of samples. Compared with previous methods, sample preparation time and/or LOQs are reduced. The method demonstrated its successful application for the analysis of different parts of several fish species. Most of the samples tested positive, mainly for perfluoropentanoic acid (PFPA), perfluorobutane sulfonate (PFBS) and perfluorooctanoic acid (PFOA) but other of the eight studied PFCs were also present.     

Direct aqueous supercritical fluid extraction coupled on-line with liquid chromatography–tandem mass spectrometry for the analysis of polyether ionophore antibiotics in water

A direct aqueous SFE system designed to extract water samples contained in vials has been coupled on-line with a reverse phase LC–MS–MS system using a single 10-port valve. An SFE trap system using C₁ stationary phase connected to a C₁₈ analytical HPLC column enabled the SFE–LC–MS–MS analysis of three polyether ionophore antibiotics in water using a step gradient. A quantitative SFE–LC–MS–MS method has been developed whereby the progress of SFE can be monitored directly on-line such that ionophore recovery profile data from a single water sample can be obtained. Using a continuous direct aqueous SFE period of 75 min, the SFE–LC–MS–MS recoveries of the ionophores were: monensin 76.2% with RSD 4.1%, lasalocid 84.6% with RSD 3.8% and narasin 91.2% with RSD 3.2%. With positive ion electrospray ionization, the SFE–LC–MS–MS system using a 4 mL water sample provided multiple reaction monitoring (MRM) limits of detection for monensin and lasalocid each equivalent to 90 ng/L whereas 30 ng/L for narasin. A two-way valve controlling carbon dioxide distribution to the SFE vessel has provided a means for the initial investigation of the recovery of ionophore sodium salts from water using static SFE.     

High-throughput determination of pesticide residues in food commodities by use of ultra-performance liquid chromatography–tandem mass spectrometry

A rapid, simple, and sensitive multiresidue method for analysis of 53 pesticides in fruit and vegetables by ultra-performance liquid chromatography (UPLC) coupled to triple-quadrupole tandem mass spectrometry (MS-MS) has been developed and validated. Prior to analysis, analytes were extracted by use of buffered QuEChERS (quick, easy, cheap, effective, rugged, safe) methodology without further cleanup for non fatty matrices. Chromatographic conditions were optimised in order to achieve a fast separation in multiple reaction monitoring (MRM) mode. Indeed, more than 50 pesticides can be separated in less then 10 min. Four common representative matrices (cucumber, orange, strawberry, and olive) were selected to investigate the effect of different matrices on recovery and precision. Mean recoveries ranged from 70 to 109% with relative standard deviations lower than 20% for all the pesticides assayed in the four selected matrices. The method has been applied to the analysis of 200 vegetable samples, and imidacloprid was the pesticide most frequently found, with concentrations ranging from 0.01 to 1.00 mg kg⁻¹. This methodology combines the advantages of both QuEChERS and UPLC-MS-MS producing a very rapid, sensitive, and reliable procedure which can be applied in routine analytical laboratories.     

Mixed-mode solid-phase extraction followed by liquid chromatography–tandem mass spectrometry for the determination of tri- and di-substituted organophosphorus species in water samples

A procedure for the determination of three phosphoric acid diesters, eight triesters and triphenylphosphine oxide (TPPO) in water samples is presented. Analytes were simultaneously concentrated using a mixed-mode (reversed-phase and anionic-exchange) solid-phase extraction (SPE) sorbent and then sequentially eluted with methanol (triesters and TPPO) followed by a 20 mM tetrabutylammonium hydrogen sulphate (TBAHS) methanolic solution, case of diesters. After that, they were determined, in two different runs, by liquid chromatography–electrospray ionization–tandem mass spectrometry (LC–ESI–MS/MS), operating the ESI source in the positive (triesters and TPPO) and negative (diesters) ionization modes. The efficiency of the extraction step varied between 70 and 105%, except in the case of tris(2-ethylhexyl) phosphate (TEHP), and it was barely affected by the type of water sample. Moreover, low signal suppression effects were noticed in the ESI ionization of extracts obtained from different environmental water samples. As a result, the standard addition methodology was only required for the accurate quantification of tri-substituted organophosphorus (OPs) species in wastewater samples. Limits of quantification of the optimized method ranged from 0.2 to 10 ng L⁻¹, depending on the sample matrix and the considered compound. The analysis of river and wastewater samples confirmed the occurrence of several tri- and di-substituted OPs in the aquatic environment, with the highest concentrations corresponding to tris(butoxyethyl) phosphate (TBEP) and tris(chloropropyl) phosphate (TCPP).     

Screening of drugs in equine plasma using automated on-line solid-phase extraction coupled with liquid chromatography–tandem mass spectrometry

A rapid liquid chromatography–tandem mass spectrometry (LC–MS–MS) method was developed for the simultaneous screening of 19 drugs of different classes in equine plasma using automated on-line solid-phase extraction (SPE) coupled with a triple quadrupole mass spectrometer. Plasma samples were first protein precipitated using acetonitrile. After centrifugation, the supernatant was directly injected into the on-line SPE system and analysed by a triple quadrupole LC–MS–MS in positive electrospray ionisation (+ESI) mode with selected reaction monitoring (SRM) scan function. On-line extraction and chromatographic separation of the targeted drugs were performed using respectively a polymeric extraction column (2 cm L × 2.1 mm ID, 25 μm particle size) and a reversed-phase C18 LC column (3 cm L × 2.1 mm ID, 3 μm particle size) with gradient elution to provide fast analysis time. The overall instrument turnaround time was 9.5 min, inclusive of post-run and equilibration time. Plasma samples fortified with 19 targeted drugs including narcotic analgesics, local anaesthetics, antipsychotics, bronchodilators, mucolytics, corticosteroids, sedative and tranquillisers at sub-parts per billion (ppb) to low parts per trillion (ppt) levels could be consistently detected. No significant matrix interference was observed at the expected retention times of the targeted ion transitions. Over 70% of the drugs studied gave detection limits at or below 100 pg/mL, with some detection limits reaching down to 19 pg/mL. The method had been validated for extraction recovery, precision and sensitivity, and a blockage study had also been carried out. This method is used regularly in the authors’ laboratory to screen for the presence of targeted drugs in pre-race plasma samples from racehorses.     

The determination of pharmaceutical residues in cooked and uncooked marine bivalves using pressurised liquid extraction, solid-phase extraction and liquid chromatography–tandem mass spectrometry

An optimised and validated method for the determination of pharmaceutical residues in blue mussels (Mytilus spp.) is presented herein, as well as an investigation of the effect of cooking (by steaming) on any potential difference in human exposure risk. Selected pharmaceuticals included two non-steroidal anti-inflammatory drugs (diclofenac and mefenamic acid), an antibiotic (trimethoprim), an anti-epileptic (carbamazepine) and a lipid regulator (gemfibrozil). An in vivo exposure experiment was set up in the laboratory in which mussels were exposed either directly by injection (10 ng) or daily through spiked artificial seawater (ASW) over 96 h. In liquid matrices, pharmaceutical residues were either determined using liquid chromatography–tandem mass spectrometry (LC-MS/MS) directly, or in combination with solid-phase extraction (SPE) for analyte concentration purposes. The extraction of pharmaceuticals from mussel tissues used an additional pressurised liquid extraction step prior to SPE and LC-MS/MS. Limits of quantification of between 2 and 46 ng L^?1 were achieved for extracted cooking water and ASW, between 2 and 64 μg L^?1 for ASW in exposure tanks, and between 4 and 29 ng g^?1 for mussel tissue. Method linearities were achieved for pharmaceuticals in each matrix with correlation coefficients of R ²?>?0.975. A selection of exposed mussels was also cooked (via steaming) and analysed using the optimised method to observe any effect on detectable concentrations of parent pharmaceuticals present. An overall increase in pharmaceutical residues in the contaminated mussel tissue and cooking water was observed after cooking.

Trace-level determination of eight cholesterol oxidation products in human plasma by dispersive liquid–liquid microextraction and ultra-performance liquid chromatography–tandem mass spectrometry

7α-Hydroxy cholesterol (7α-OHC), 25-hydroxy cholesterol (25-OHC), 27-hydroxy cholesterol (27-OHC), 4β-hydroxy cholesterol (4β-OHC), 7α-hydroxy-4-cholesten-3-one (7α-C4), 5β-cholestane-3α, 7α, 12α-triol (5β-Triol), cholic acid (CA), and chenodeoxycholic acid (CDCA) are known biomarkers of neurodegenerative diseases. A method for their simultaneous determination in human plasma has been optimized using dispersive liquid–liquid microextraction and ultra-performance liquid chromatography–tandem mass spectrometry. The limits of quantification of the target compounds were in the range of 0.3–3.3?µg/L. The precision achieved by this method was less than 13.4% for intraday and interday analyses. The proposed method was used to analyze eight cholesterol oxidation products in 30 human plasma samples. The analytical results were in a concentration range of 1.6–87.4?µg/L for 7α-OHC, 6.3–58.2?µg/L for 25-OHC, 12.1–98.5?µg/L for 27-OHC, 5.7–64.8?µg/L for 4β-OHC, 1.5–124.1?µg/L for 7α-C4, 0.5–16.5?µg/L for 5β-Triol, 13.1–245?µg/L for CA, and 19.6–487?µg/L for CDCA in the samples. The method may be used for the analysis of biomarkers of neurodegenerative diseases.     

Optimization of antibiotic analysis in water by solid-phase extraction and high performance liquid chromatography–mass spectrometry/mass spectrometry

This paper describes the development of an optimized method based on solid-phase extraction (SPE) followed by liquid chromatography–electrospray ionization tandem mass spectrometry (LC–MS/MS) for the simultaneous analysis of ten antibiotic compounds including tetracyclines, sulfonamides, macrolides and quinolones. LC–MS/MS sensitivity has been optimized by alterations to both LC and MS operations. Of the two high resolution columns tested, Waters Symmetry C₁₈ endcapped and Agilent Zorbax Bonus-RP, the latter was found to show better performance in producing sharp peaks and clear separation for most of the target compounds. Optimization of the MS fragmentation collision and cone energy enhanced the peak areas of the target analytes. The recovery of the target compounds from water samples was most efficient on Waters Oasis HLB SPE cartridge, while methanol was shown to be the most suitable solvent for desorbing the compounds from SPE. In addition, acidification of samples prior to SPE was shown to enhance the recovery of the compounds. To ensure a satisfactory recovery, the flow rate through SPE should be maintained at ≤10 mL min⁻¹. The method was successfully applied to the analysis of antibiotics from environmental water samples, with concentrations being <LOD in tap water, between <LOD to 28 ng L⁻¹ in river water and between <LOD to 230 ng L⁻¹ in sewage effluent.     

Development of a simple extraction and clean-up procedure for determination of organochlorine pesticides in soil using gas chromatography–tandem mass spectrometry

A procedure based on QuEChERS extraction and a simultaneous liquid–liquid partition clean-up was developed. The procedure involved extraction of hydrated soil samples using acetonitrile and clean-up by liquid–liquid partition into n-hexane. The hexane extracts produced were clean and suitable for determination using gas chromatography–tandem mass spectrometry (GC–MS/MS). The method was validated by analysis of soil samples, spiked at five levels between 1 and 200 μg kg⁻¹. The recovery values were generally between 70 and 100% and the relative standard deviation values (%RSDs) were at or below 20%. The procedure was validated for determination of 19 organochlorine (OC) pesticides. These were hexachlorobenzene (HCB), α-HCH, β-HCH, γ-HCH, heptachlor, heptachlor epoxide (trans), aldrin, dieldrin, chlordane (trans), chlordane (cis), oxychlordane, α-endosulfan, β-endosulfan, endosulfan sulfate, endrin, p,p′-DDT, o,p′-DDT, p,p′-DDD and p,p′-DDE. The method achieved low limits of detection (LOD; typically 0.3 μg kg⁻¹) and low limits of quantification (LOQ; typically 1.0 μg kg⁻¹). The method performance was also assessed using five fortified soil samples with different physico-chemical properties and the method performance was consistent for the different types of soil samples. The proposed method was compared with an established procedure based on Soxtec extraction. This comparison was carried out using six soil samples collected from regions of Pakistan with a history of intensive pesticide use. The results of this comparison showed that the two procedures produced results with good agreement. The proposed method produced cleaner extracts and therefore led to lower limits of quantification. The proposed method was less time consuming and safer to use. The six samples tested during this comparison showed that soils from cotton growing regions contained a number of persistent OC residues at relatively low levels (<10 μg kg⁻¹). These residues were α-HCH, γ-HCH, heptachlor, chlordane (trans), p,p′-DDT, o,p′-DDT, p,p′-DDD, p,p′-DDE, β-endosulfan and endosulfan sulfate.     

Quantitative determination of triclocarban in wastewater effluent by stir bar sorptive extraction and liquid desorption–liquid chromatography–tandem mass spectrometry

Triclocarban is an antimicrobial and antibacterial agent found in personal care products and subsequently is a prevalent wastewater contaminant. A quantitative method was developed for the analysis of triclocarban in wastewater effluents using stir bar sorptive extraction–liquid desorption (SBSE–LD) followed by liquid chromatography–tandem mass spectrometry (LC–MS/MS) by means of an electrospray interface. A stir bar coated with polydimethylsiloxane (PDMS) is placed within a vial containing wastewater effluent and is stirred for an hour at room temperature. The PDMS stir bar is then placed in a LC vial containing methanol and is desorbed in a sonicator bath. The methanol is evaporated to dryness and reconstituted in 75% methanol. Spike and recovery experiments in groundwater that did not contain native concentrations of triclocarban were performed at 0.5 μg/L and were 93 ± 8%. Recoveries in wastewater effluent that were corrected for the background levels of triclocarban were 92 ± 2% and 96 ± 5%, respectively, when spiked with 0.5 and 5 μg/L of triclocarban. The precision of the method as indicated by the relative standard error was 2%. The limit of quantitation was 10 ng/L. The SBSE–LD–LC/MS/MS method was applied to wastewater effluent samples collected from northeast Ohio. Triclocarban was quantitated in all five effluent samples, and its concentration ranged from 50 to 330 ng/L. The described method demonstrates a simple, green, low-sample volume, yet, sensitive method to measure triclocarban in aqueous matrices.     

Trace determination of nine haloacetic acids in drinking water by liquid chromatography–electrospray tandem mass spectrometry

A simple, fast and sensitive liquid chromatography–electrospray tandem mass spectrometry method was established for trace levels of nine haloacetic acids (HAAs) in drinking water. Water samples were removed of residual chlorine by adding l-ascorbic acid, and directly injected after filtered by 0.22 μm membrane. Nine HAAs were separated by liquid chromatography in 7.5 min, and the limits of detection were generally between 0.16 and 0.99 μg/L except for chlorodibromoacetic acid (1.44 μg/L) and tribromoacetic acid (8.87 μg/L). The mean recoveries of nine target compounds in spiked drinking water samples were 80.1–108%, and no apparent signal suppression was observed. Finally, this method was applied to determine HAAs in the tap water samples collected from five waterworks in Shandong, China. Nine HAAs except for monochloroacetic acid, monobromoacetic acid, dibromochloroacetic acid and tribromoacetic acid were detected, and the total concentrations were 7.79–36.5 μg/L. The determination results well met the first stage of the Disinfectants/Disinfection By-Products (D/DBP) Rules established by U.S.EPA and Guidelines for Drinking-water Quality of WHO.     

Analysis of 29 per- and polyfluorinated compounds in water,sediment, soil and sludge by liquid chromatography–tandem mass spectrometry

Several analytical methods were optimised for the analysis of 29 per- and polyfluoroalkyl substances (PFASs), including perfluorocarboxylic acids, perfluoroalkyl sulphonic acids and fluorotelomers (FTs), such as sulphonate, saturated carboxylic acid, unsaturated carboxylic acid, sulphonamide and sulphonamide betaine (FTAB), in environmental samples in order to assess pollution by PFASs around heavily contaminated sites. Non-filtered water samples were extracted, purified and pre-concentrated by a solid-phase extraction (SPE) procedure. Solid samples (sediments, soils and sludges) were extracted through solvent extraction under acidic conditions and thereafter purified and pre-concentrated using the same SPE procedure as for the water samples. An ultra-high performance liquid chromatography coupled to tandem mass spectrometry in negative electrospray ionisation mode was employed to separate and detect targeted compounds. Twelve labelled internal standards were used to provide an adequate correction compensating for matrix effects. The limits of quantification (LOQs) were between 4 and 10 ng/L in water depending on the analytes. For solid samples, the LOQs were 2 ng/g dry weight (dw) in sediments and soils, and 20 ng/g dw in sludges for all analytes. A surrogate parameter method based on the carboxylation of perfluoroalkyl acid precursors under basic pH conditions was furthermore implemented to estimate the occurrence of non-targeted PFAS compounds. In order to evaluate the reliability of these analytical methods, environmental samples collected around a training area in France, where aqueous fire-fighting foam is used, were analysed. Of all the compounds detected in these environmental samples, 6:2 FTAB was found in the highest concentrations.     

Enantioselective separation and simultaneous determination of fenarimol and nuarimol in fruits, vegetables, and soil by liquid chromatography–tandem mass spectrometry

A method for simultaneous enantioselective determination of fenarimol and nuarimol in apple, grape, cucumber, tomato, and soil was developed using liquid chromatography–tandem mass spectrometry. The enantioseparation results of the two fungicides through three different cellulose-based chiral columns are discussed. The influence of column temperature on the resolution of the enantiomers of the two fungicides was examined. Complete enantioseparation of the two fungicides’ enantiomers was obtained on a cellulose tris(4-methylbenzoate) column (Lux Cellulose-3) at 25?°C using methanol and 0.1?% formic acid solution (80:20, v/v) as mobile phase. The linearity, matrix effect, recovery, and precision were evaluated. Good linearity was obtained over the concentration range of 1–500?μg?L^?1 for each enantiomer in the standard solution and sample matrix calibration solution. There was no significant matrix effect in apple, grape, cucumber, or tomato samples, but signal suppression was typically observed with the soil extracts. The mean recoveries, repeatability, and reproducibility were 76.5–103?%, 2.1–9.0?%, and 4.2–11.8?%, respectively. The limit of quantification for enantiomers of the two fungicides in fruits, vegetables and soil was 5?μg?kg^?1. Moreover, the absolute configuration of the enantiomers of fenarimol and nuarimol was determined from a combination of experimentally determined and predicted electronic circular dichroism spectra.

Stir-bar-sorptive extraction and ultra-high-performance liquid chromatography–tandem mass spectrometry for simultaneous analysis of UV filters and antimicrobial agents in water samples

Stir-bar-sorptive extraction (SBSE) with liquid desorption (LD) and ultra-high-performance liquid chromatography–electrospray ionization triple-quadrupole tandem mass spectrometry (UHPLC–(ESI)MS–MS) were used for analysis of six personal care products in environmental water: four UV filters (2,2-dihydroxy-4-methoxybenzophenone, benzophenone-3, octocrylene, and octyldimethyl-p-aminobenzoic acid) and two antimicrobial agents (triclocarban and triclosan). Experimental conditions that affect SBSE-LD sorption efficiency (extraction time and temperature, sample pH, and ionic strength) and desorption efficiency (solvent, temperature, and time) were optimized. The method proved to be sensitive—a 50-mL sample was used to determine these compounds in environmental waters at trace levels. The detection limits of the analytical method were 2.5 ng L⁻¹ for river water and 5–10 ng L⁻¹ for effluent and influent sewage water. In river waters, benzophenone-3 was found at levels from 6 ng L⁻¹ to 28 ng L⁻¹ and triclosan at levels <LOQ. Benzophenone-3 was found between 75 and 127 ng L⁻¹ in influent sewage, whereas concentrations of benzophenone-3 and triclosan were commonly below 25 ng L⁻¹ in effluent sewage.